- Substituent effects and threshold energies for the unimolecular elimination of HCl (DCl) and HF (DF) from chemically activated CFCl2CH3 and CFCl2CD3
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Combination of CFCl2 and methyl-d0 and -d3 radicals form CFCl2CH3-d0 and -d3 with 100 and 101 kcal/mol of internal energy, respectively. An upper limit for the rate constant ratio of disproportionation to combination, kd/kc, for Cl transfer is 0.07 ± 0.03 for collision of two CFCl2 radicals and 0.015 ± 0.005 for CH3 and CFCl2 radicals. The chemically activated CFCl2CH3 undergoes 1,2-dehydrochlorination and 1,2-dehydrofluorination with rate constants of 3.9 × 109 and 4.9 × 107 s-1, respectively. For CFCl2CD3 the rate constants are 8.7 × 108 s-1 for loss of DCl and 1.1 × 107 s-1 for DF. The kinetic isotope effect is 4.4 ± 0.9 for HCl/DCl and appears to be identical for HF/DF. Threshold energies are 54 kcal/mol for loss of HCl and 68 kcal/mol for HF; the E0's for the deuterated channels are 1.4 kcal/mol higher. Comparison of these threshold energies with other haloethanes suggests that for HF and HCl elimination the transition states are developing charges of different signs on the carbon containing the departing halogen and that chlorine and fluorine substituents exert similar inductive effects.
- McDoniel, J. Bridget,Holmes, Bert E.
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- γ-Alumina-supported boron trifluoride: Catalysis, radiotracer studies and computations
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The irreversible adsorption of boron trifluoride on calcined γ-alumina and amorphous chromia, in both cases at room temperature, has been studied using [18F]-labelled BF3. Although the resulting γ-alumina surface has some catalytic activity for the room temperature fluorination by anhydrous HF of CH3CCl3 under static conditions, its activity is far lower than that of γ-alumina, which has been fluorinated with SF4, nominally at room temperature. A possible explanation for the observed behaviour is given.
- Klap?tke, Thomas M.,McMonagle, Fiona,Spence, Ronald R.,Winfield, John M.
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- Liquid-phase fluorination of 1,1,1-trichloroethane
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The reaction of HF with SbCl5 at 60 deg C and 1 MPa provides antimony mixed halides whose empirical formulae have been determined.The product is a mixture of SbClF4 and SbClF2 solvated by HF and its activity has been measured for the conversion of 1,1,1-trichloroethane (F140a) into mono- and difluorochloroethane (F141b and F142b).
- Brunet, S.,Batiot, C.,Barrault, J.,Blanchard, M.
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- Fluorinated γ-Alumina. Catalytic Fluorination of 1,1,1-Trichloroethane at Ambient Temperature
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γ-Alumina, fluorinated with sulphur tetrafluoride followed by treatment with 1,1,1-trichloroethane, behaves as a catalyst for the room temperature fluorination of CH3CCl3 with anhydrous HF, giving a mixture of chlorofluorohydrocarbons.
- Thomson, James,Webb, Geoffrey,Winfield, John M.
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- Method of making difluoromethane, 1,1,1-trifluoroethane and 1,1-difluoroethane
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A process for the production of difluoromethane (HFC-32), 1,1,1-trifluoroethane (HFC-143a) and 1,1-difluoroethane (HFC-152a). In the process the following steps are employed: (a) providing a reaction vessel, (b) providing in the reaction vessel activated carbon impregnated with a strong Lewis acid fluorination catalys selected from halides of As, Sb, Al, TI, In, V, Nb, Ta, Ti, Zr and Hf, (c) activating the catalyst by passing through the activated carbon impregnated with a strong Lewis acid fluorination catalyst anhydrous hydrogen fluoride gas and chlorine gas, (d) contacting, in a vapor state in the reaction vessel containing the activated catalyst, hydrogen fluoride and one or more halogenated hydrocarbons selected from chlorofluoromethane, dichloromethane, 1,1,1-trichloroethane, vinyl chloride, 1,1-dichloroethylene, 1.2-dichloroethylene, 1,2-dichloroethane, and 1,1-dichloroethane for a time and at a temperature to produce a product stream comprising hydrofluorocarbon product(s) corresponding to the chlorinated hydrocarbon reactant(s), and one or more of hydrogen chloride, unreactacted chlorinated hydrocarbon reactant(s), under-fluorinated intermediates, and unreacted hydrogen fluoride, and (e) separating the hydrofluorocarbon product(s) from the product stream.
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(2010/02/14)
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- Generation of radical species in surface reactions of chlorohydrocarbons and chlorocarbons with fluorinated gallium(III) oxide or indium(III) oxide
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The reactions of C1 and C2 chlorohydrocarbons and chlorocarbons have been studied with the Lewis acid catalysts fluorinated gallium(III) oxide and fluorinated indium(III) oxide, respectively. Product analysis shows chlorine-for-fluorine exchange reactions together with the formation of 2-methylpropane and its chlorinated analogues 2-chloromethyl-1,3-dichloropropane and 2-chloromethyl-1,2,3-trichloropropane. Reactivities of the chlorohydrocarbon probe molecules show fluorinated gallium(III) oxide to be a stronger Lewis acid than fluorinated indium(III) oxide. The formation of the symmetrical butyl compounds is consistent with the generation of surface radical species and is also consistent with a 1,2-migration mechanism operating within radical moieties at the Lewis acid surface.
- Thomson
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p. 1881 - 1885
(2007/10/03)
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- Production of organic fluorine compounds
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A process is disclosed for hydrofluorinating an olefinic hydrocarbon of the formula where X, X' and X" are the same or different and are hydrogen or halo and R' is hydrogen or C1 -C6 alkyl, with hydrogen fluoride. The process is carried out by admixing the olefinic hydrocarbon with hydrogen fluoride in an imidofluoride hydrogen fluoride solvent having the formula where R is C1 to C6 alkyl, C1 to C6 alkyl substituted with halo or C6 to C10 aryl either unsubstituted or substituted with alkyl and η is 0 or an integer that is at least 1.
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- Fluorination process using hydrogen fluoride-containing fluorinating agents
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Fluorination processes using hydrogen fluoride-containing fluorinating agents that are safely and easily handled, transported, and stored and that also exhibit good reactivity are provided. More particularly, the invention provides processes for producing fluorinated products using fluorinating agents comprising hydrogen fluoride and a carrier that may be an acid salt or a water-soluble polymer.
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- Liquid phase fluorination process and fluorinated organic products resulting therefrom
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In an improved process and plant for carrying out liquid phase fluorination in the presence of a catalyst, consisting in reacting hydrofluoric acid and an organic starting material in a reaction zone, and in separating, in a separating zone, reactional mixture and at least one light fraction containing the desired fluorinated organic products and at least a first part of the sub-fluorinated organic products formed, and a heavy fraction that includes the remainder of the sub-fluorinated organic products formed, and further comprising partial condensation of the said light fraction in order to obtain a gaseous phase containing the desired fluorinated organic products and a liquid phase containing said first part of the said sub-fluorinated organic products, said heavy fraction being returned to said reaction zone and said liquid phase being returned as a reflux to the top of the separation zone, intermediate recovery is carried out at, or in the proximity of, the lower portion of said separation zone.
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- Method for preparing 1,1-dichloro-1-fluoroethane
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A more efficient reaction mechanism is provided for producing 1,1-dichloro-1-fluoroethane (HCFC-141b) by reacting vinylidene chloride with hydrogen fluoride in the liquid phase in the presence of a catalyst and a sulfone solvent or a nitroalkane or nitroarene solvent. In particular, by using a titanium tetrafluoride catalyst in conjunction with tetramethylene sulfone solvent, most all the vinylidene chloride reagent can be converted to HCFC-141b to the virtual exclusion of unwanted, closely associated byproducts like 1,1-difluoro-1-chloroethane (HCFC-142b) and 1,1,1-trifluoroethane (HFC-143a), while reducing the production of tars to a minimum.
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- Method for preparing 1,1-dichloro-1-fluoroethane
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A more efficient reaction mechanism is provided for producing 1,1-dichloro-1-fluoroethane (HCFC-141b) by reacting vinylidene chloride with hydrogen fluoride in the liquid phase in the presence of a catalyst and sulfone-based or nitrated solvent. In particular, by using a titanium tetrafluoride catalyst in conjunction with tetramethylene sulfone solvent, most all the vinylidene chloride reagent can be converted to HCFC-141b to the virtual exclusion of unwanted, closely associated byproducts like 1,1-difluoro-1-chloroethane (HCFC-142b) 1,1,1-trifluoroethane (HFC-143a), while reducing the production of tars to a minimum.
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- Room-temperature Catalytic Fluorination of C1 and C2 Chlorocarbons and Chlorohydrocarbons on Fluorinated Fe3O4 and Co3O4
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A study of the room-temperature reactions of a series of C1 and C2 chlorohydrocarbon and chlorocarbon substrate molecules with fluorinated iron(II,III) oxide and cobalt(II,III) oxide has been conducted.The results show that fluorinated iron(II,III) oxide exhibits an ability to incorporate fluorine into the following substrates in the order: Cl2C=CCl2 > H2C=CCl2 > CH3CCl3 > CHCl3 > CH2Cl2 > CH2ClCCl3 > CCl4 > CHCl2CHCl2.The fluorinated cobalt(II,III) oxide gave the reactivity series CHCl3 > CCl4 > H2C=CCl2 > CHCl2CHCl2 > CH2Cl2 > CH3CCl3 > CCl2CCl2 > CH2ClCl3.Reactions of C1 chlorohydrocarbon or chlorocarbon probe molecules with fluorinated Fe3O4 gave predominately C1 chlorofluorohydrocarbon and chlorofluorocarbon products, respectively, whereas fluorinated cobalt(II,III) oxide produced predominately C2 chlorofluorohydrocarbon and chlorofluorocarbons.For fluorinated Co3O4 the distribution of C2 products obtained from C1 chlorohydrocarbon precursor molecules is consistent with the formation of radical intermediates at strong Lewis acid surfaces.C2 chlorohydrocarbons exhibit a fluorine for chlorine (F-for-Cl) exchange reaction through the catalytic dehydrochlorination of the substrate to the alkenic intermediate.The F-for-Cl exchange process was dependent upon the ability of the substrate material to undergo dehydrochlorination; the inability of a substrate to undergo dehydrochlorination results in the fluorination process proceeding through the formation of chlorocarbon or chlorohydrocarbon radical intermediates.
- Thomson, James
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p. 3585 - 3590
(2007/10/02)
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- INVESTIGATIONS IN THE REGION OF INDUSTRIAL FLUORINATED COMPOUNDS
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The synthesis and properties of ozone-friendly fluorohydrocarbons, fluoroolefins, and fluorinated compounds with functional groups (acids, alcohols, esters, and others), used for the creation of effective surfactants, ion-exchange membranes for various purposes, heat-resistant oils, and greases, were investigated.A technology was developed for the production of highly pure fluorinated compounds for microelectronics, fiber optics, and medicine.
- Maksimov, B. N.
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p. 1935 - 1940
(2007/10/03)
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- Liquid-phase fluorination and dehydrochlorination of 1,1,1-trichloroethane
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During the liquid-phase fluorination of 1,1,1-trichloroethane with SbCl5*HF, 1,1-dichloroethene is formed.This reacts to give linear and branched oligomers.The hydrolysis of these by-products affords 3,5-dichlorophenol, 6-methyl-4-chloro-2-pyran-2-one and 2-methyl-5,7-dichlorochromone whose source is the acid-catalyzed reaction of water with the trimer and pentamer of 1,1-dichloroethene.
- Brunet, Sylvette,Batiot, Catherine,Barrault, Joeel,Blanchard, Michel,Coustard, Jean-Marie
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p. 227 - 232
(2007/10/02)
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- Purification of 1,1-dichloro-1-fluoroethane
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The present invention provides a process for the purification of 1,1-dichloro-1-fluoroethane comprising the steps of: (a) reacting anhydrous hydrogen fluoride with 1,1,1-trichloroethane or vinylidene chloride containing dichloroacetylene to form 1,1-dichloro-1-fluoroethane; and (b) passing the 1,1-dichloro-1-fluoroethane through activated carbon to substantially remove unsaturated impurities. In particular, the present process reduces the amounts of dichloroacetylene and vinylidene chloride in the 1,1-dichloro-1-fluoroethane product so as to meet the current specifications set forth by the Panel for Advancement of Fluorocarbon Test. The purified 1,1-dichloro-1-fluoroethane product is useful as a blowing agent and a solvent.
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- TaF5 and NbF5 as fluorination catalysts
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A halogenated alkene is reacted with HF in the presence of TaF5 or NbF5 to produce a fluorinated alkane. Exemplary is the reaction of tetrachloroethene with HF in the presence of TaF5 to produce 1,2,2-trichloro-1,1-difluoroethane and 1,1,2,2-tetrachloro-1-fluoroethane.
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